Aquarium Heaters

What Kinds of Aquarium Heaters Are There and What Is My Fish Tank Heater For?

(The First Tank Guide)

An aquarium heater is a piece of aquarium equipment used to keep
the fish tank water warm - or, rather, to keep the fish tank from
getting below a particular temperature.

A heater will be necessary for your fish tank if the temperature in
the room the fish are being kept in is regularly below the preferred
temperature for the fish, or if the temperature in the room ever drops
below the minimum temperature that is safe for the fish. In general,
an aquarium will require a heater for tropical fish, but not for
temperate fish.

Most aquariums have heaters, but there are often questions about
these very common pieces of fish tank
equipment. There are several types of aquarium heaters available,
both internal (the heating element is in the fish tank) and external
(the heating element is not in the fish tank). External heaters come
in two varieties: in-line heaters and in-filter heaters, though there
occasionally mention of in-sump heaters (don't worry, I'll cover those
too). Internal heaters come in three varieties: hanging, submersible,
and substrate. All heaters also need a thermostat to switch the heater on and
off as necessary to maintain the desired temperature.

Hanging Aquarium Heaters

Hanging heaters are the most common and least expensive heaters
available. Almost all aquarium kits contain a hanging heater to help
new aquariists maintain correct water temperature for freshwater
tropical fish.

These heaters hang (as the name implies) off the top edge of the fish tank, usually at the back of the aquarium,
with a glass tube containing the heater element set into the water. A
hanging heater will require you to cut an opening in the aquarium hood to accommodate the head
of the heater, but most aquarium hoods come with a section designed to
be cut to accommodate hanging heaters or filters.

It is also important to make sure you secure the heater to the back
of the aquarium correctly so that it does not get knocked about, as
this could break the glass sheath on the heater, posing a risk of
electrocution to you and your fish, and possibly a risk of fire.

It is important to note that hanging heaters are inappropriate -
even dangerous - for marine or brackish water aquariums, as the salt
can get into the tube and cause corrosion or electrical shorts.

Submersible Aquarium Heaters

Submersible aquarium heaters can be fully immersed in the aquarium
water. Because these heaters are completely submersible, they are
generally more efficient than the hanging aquarium heaters. These
heaters can be placed fairly low in the water. submersible aquarium
heaters can be positioned vertically, horizontally, or at an angle,
however, they tend to work best when positioned vertically or
horizontally. If your submersible heater has an internal thermostat,
it is usually more efficient if you position it horizontally in the
tank, and fairly low in the water column. This will help the
thermostat get an accurate reading on the tank temperature and
correctly activate and deactivate the heater.

Submersible heaters are usually attached to the back of the
aquarium by a clip with suction cups. It is important that you keep
the heater off of the gravel, as the difference in heat conductivity
between the water and the gravel could result in the glass of the
heater cracking. It is also important that you provide enough space
between the heater and the gravel or the side of the tank to insure
that no fish will get caught against the heater and get burned.

Aquarium Substrate Heaters

Aquarium substrate heaters are the least common of the internal
aquarium heaters for hobby or pet keeping use. Substrate heaters
consist of a coil or grid of wire in an insulator which is buried in
the aquarium gravel or
substrate. The wire itself is the element for the heater, and when
the heater is on, this wire becomes warm and heats the gravel in the
tank. The heat is then radiated from the gravel to warm the
water. When the water becomes warm enough, the thermostat will switch
the heater off.

Substrate heaters are supposed to be particularly beneficial for
planted tanks where the gravel may act as an insulator and keep the
plants' roots too cool. With a substrate heater, this concern is
alleviated because the heater keeps the gravel nice and warm, and
keeps the plant roots happy and comfortable.

In-Line Aquarium Heaters

In-line aquarium heaters are external aquarium heaters which are
self-contained, but reside in or along a section of external
plumbing. This is usually the plumbing for some kind of aquarium filter or other piece of external
aquarium equipment.

In-line aquarium heaters require a water pump to move the water
through them, though this can usually be piggy backed with a trickle filter, a canister filter, or a UV sterilizer, and all the heater requires
is water flow. The water is pumped out of the tank, through a tube or
pipe, through the heater, and the heated water is returned to the
tank.

In-Filter Aquarium Heaters

Some models of aquarium filters, usually
canister filters, but sometimes power filters or other varieties, come with
built-in heater elements. These heaters heat the water as it goes
through the filter, returning heated and cleaned water to the
aquarium. Since these filters are inside of - and usually integral to
- the filter, they are referred to as in-filter heaters.

In-Sump Aquarium Heaters

Occasionally you may hear about in-sump aquarium heaters or sump
heaters.

Usually an in-sump aquarium heater is nothing more than a
submersible aquarium heater that is set up in the sump of a trickle
filter rather than in the fish tank itself. This configuration
provides better safety for the fish by minimizing the risk of the
aquarium heater getting damaged by a belligerent fish such as an Oscar, making it much less likely that something
would get knocked against or fall onto the aquarium heater and
breaking it, making is less likely that the aquarium heater would get
damages while the aquarium was being cleaned, and by making it
impossible for a fish to get caught under or behind the aquarium
heater and getting burned.

Other Considerations

It is important to make sure that your aquarium heater is set up so
that it is unlikely that a fish will get caught between the heater and
something else, such as a decoration, the side of the aquarium, or the
aquarium gravel. It is also important to make sure that there are
plenty of other hiding places in the tank through proper aquarium decoration so that the fish
do not feel that the only hiding place is against or behind the
heater. A fish that gets stuck between the aquarium heater and
something else is definitely at risk getting severely burned, and even
fish that feel there is no place else to hide can receive
life-threatening burns from your aquarium heater.

Make sure that there is water between the aquarium heater and any
other surface, especially around the element inside the heater. If
the glass sheath of the aquarium heater touches the aquarium glass,
gravel, or a decoration, this could cause a temperature gradient in
the glass which will cause the glass to shatter. This exposes you and
your fish to electrocution, and can pose as a fire hazard.

When you first set up your fish tank, or when you get a new heater
for your aquarium, remember to always let the new aquarium heater sit
in the aquarium water, with the heater properly set up, for at least
half an hour before you plug the heater in or begin to set the thermostat. This will give the
heater time to reach temperature equilibrium and prevent the glass
from breaking due to temperature differences when the heater element
comes on. Similarly, it is important to make sure that the heater has
been unplugged for half an hour or more before removing it from the
fish tank to insure that the glass is cool and unlikely to break on
contact with the air (or some other surface) or due to water
evaporating off the glass, and to prevent the heater from causing
damage by burning or melting anything it may be set on.

What If I Do Not Want a Heater in My Aquarium?

An aquarium heater is a very important part of your fish tank set up
if you are going to have tropical fish. Many beginners forgo the
heater and instead select temperate water fish. There are a variety of
goldfish and other temperate fish which will
do quite nicely at room temperature or sometimes even cooler.

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